This new study builds directly on a previous study by the applicant, which found that participation in 12-step groups specially designed for dually diagnosed persons (Double Trouble in Recovery; DTR), was associated with drug abstinence and improved psychiatric outcomes. This application proposes to extend the previous effectiveness study (which recruited active DTR participants only and had no comparison sample) by conducting a quasi-experimental intervention study with a 1-year prospective follow-up. The Specific Aims are: 1. To determine whether adding dual-focus 12-step self-help groups to regular treatment for patients dually-diagnosed with drug use and mental health disorders can improve behavioral outcomes. Dually-diagnosed persons (N=126) enrolling in an outpatient or a day treatment mental health program will be followed for one year prior to the introduction of DTR groups. After the introduction of DTR groups, a second cohort of newly enrolled patients (N=150) will be followed. The primary outcome variable is substance use; secondary outcomes are medication adherence, treatment utilization and psychiatric symptoms. 2. To determine whether exposure to DTR groups increases the likelihood and consistency of attendance and involvement in community-based traditional 12-step groups (e.g., AA, NA). 3. To determine whether the recovery outcomes postulated to be associated with DTR are mediated by participation in traditional 12-step groups. 4. To examine DTR affiliation behaviors and the mediating role that DTR therapeutic processes have on substance use and other behavioral outcomes. The study's inclusion of subjects naive to DTR groups will provide an opportunity to determine the personal, treatment and environmental variables that: a) Predict the level of DTR affiliation and; b) mediate between DTR affiliation and subsequent behavioral outcomes. Drawing upon a theory-driven model, a comprehensive set of mediating variables will be investigated, including both putative "common process" factors e.g. motivation, and factors especially pertinent to self-help e.g., reciprocal learning and 12 step attitudes and beliefs. 5. To conduct a process evaluation focusing on the implementation and on-going growth and development of the DTR groups (in the study clinics), as well as DTR group climate.